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LPRS Preliminary Data Sheet Easy-Radio ER400TRS Transceiver The Easy-Radio ER400TRS intelligent radio transceiver incorporates EasyRadio technology to provide a high performance, simple to use radio device that can bi-directionally transfer serial data over a range of up to 250 metres Line Of Sight (LOS). The transceiver operates on the Pan-European 433MHz frequency band from a 3.6V supply and is housed in a space saving Single-In-Line (SIL) package. Serial input and output simplify interface to host systems and the embedded software reduces design and development time significantly. This data sheet describes the electrical and physical characteristics of the device. Operation of the software is described in the ‘Easy-Radio Software Guide’, which should be read in conjunction with this data sheet. Features Crystal controlled synthesiser for frequency accuracy Highly selective front-end, 175KHz improves range 10mW Transmit RF power output Serial Input & Output for transparent data transmission Low operating voltage - 3.6 Volts – Single Lithium Cell Low power consumption: <23mA in Transmit mode 12.5mA in Receive mode User programmable: Frequency of operation Data Rate Output Power Applications Handheld Terminals Environmental Sense & Control Vehicle to Base Station Data Transfer Remote Data Acquisition Electronic Point of Sale equipment Description The Easy-Radio 400 Transceiver is a complete sub-system that combines a high performance very low power RF transceiver, a microcontroller and a voltage regulator. (Figure 1) The microcontroller programmes the functions of the RF transceiver and provides the interface to the host system via a serial input/output. It also contains programmable EEPROM memory that holds configuration data for the various transceiver operating modes. The microcontroller also relieves the host from the intensive demands of searching for signals within the noise, recovering the received data and transmitting data in a suitable format. A Received Signal Strength Indicator output can be optionally used to measure received signal levels. The module connects to a 50 Ohm antenna such as a whip, helical or PCB loop. Antenna RSSI Output Regulator Vcc Micro Controller Serial Data Input RF Transceiver Serial Data Output Host Ready Input Busy Output Ground Figure 1 Easy-Radio Transceiver Block Diagram The Serial Data Input and Serial Data Output operate at the standard 19,200 Baud and the two handshake lines provide optional flow control to and from the host. The Easy-Radio Transceiver can accept and transmit up to 192 bytes of data, which it buffers internally before transmitting in an efficient over-air code format. Any other Easy-Radio Transceiver within range that ‘hears’ the transmission will decode the message and place the recovered data within a receive buffer that can then be unloaded to the receiving host for processing and interpretation. Transmission and reception are bi-directional half duplex i.e. transmit OR receive but not simultaneously. Easy-Radio Data sheet ER400TRS 1-1 Copyright LPRS 2002. Iss. 1-1 October 2002 Page 1 of 7 LPRS Preliminary Data Sheet Easy-Radio ER400TRS Transceiver Application & Operation Figure 2 shows a typical system block diagram comprising hosts (user’s application) connected to EasyRadio Transceivers. The hosts (A & B) will be monitoring (collecting data) and/or controlling (sending data) to some real world application. Serial Data Output Serial Data Input Host (A) Busy Serial Data Output RF Link Easy-Radio Transceiver (A) Easy-Radio Transceiver (B) Host Ready Serial Data Input Busy Host (B) Host Ready Figure 2 Typical System Block Diagram The hosts provide serial data input and output lines and two ‘handshaking’ lines that control the flow of data to and from the Easy-Radio Transceivers. The ‘Busy’ output line, when active, indicates that the transceiver is undertaking an internal task and is not ready to receive serial data. The ‘Host Ready’ input is used to indicate that the host is ready to receive the data held in the buffer of the Easy-Radio Transceiver. The host should check before sending data that the ‘Busy’ line is not high, as this would indicate that the transceiver is either transmitting or receiving data over the radio link. It should also pull the ‘Host Ready’ line low and check that no data appears on the Serial Data Output line. Detailed operation of interfacing, handshaking (including timing) is described in the ‘Easy-Radio Software Guide’. Easy-Radio Data sheet ER400TRS 1-1 Copyright LPRS 2002. Iss. 1-1 October 2002 Page 2 of 7 LPRS Preliminary Data Sheet Easy-Radio ER400TRS Transceiver Pin Out 37.0mm 14.0mm 4.0mm Top View 15.46mm 1 2 3 4 5 6 7 8 9 Pin Pitch 2.54 mm PCB Hole Size 1.0 mm Pin Description Pin No Name Description Notes 1 2 Antenna RF Ground See Note 3 4 RSSI Busy Output 5 6 7 8 Serial Data Out Serial Data In Host Ready Input Vcc 9 Ground 50 Ohm RF input/output. Connect to suitable antenna. RF ground. Connect to antenna ground (coaxial cable screen braid) and local ground plane. Internally connected to other Ground pins. Received Signal Strength Indication Digital Output to indicate that transceiver is ready to receive serial data from host. Digital output for received data to host Digital input for serial data to be transmitted Digital Input to indicate that Host is Ready to receive serial data from transceiver Positive supply pin. +3.3 to +5.5 Volts. This should be a ‘clean’ noise free supply with less than 25mV of ripple. Connect to supply 0 Volt and ground plane See Note CTS function RTS function Checklist 1. The module operates internally from an on board 3.3 Volt low drop regulator. The logic levels of the input/output pins are therefore between 0 Volt and 3.3 Volts. (See specifications). 2. The serial inputs and outputs are intended for connection to a UART or similar low voltage logic device. Do not connect any of the inputs or outputs directly to an RS232 port. The transceiver module may be permanently damaged by the voltages (+/- 12V) present on RS232 signal lines. See Application Circuit (Figure 4) for typical connection to an RS232 port via MAX232 interface IC. 3. The ‘Host Ready Input’ should be tied to 0 Volt (Ground) if not used. 4. The ‘Serial Data In’ should be tied to Vcc if not used. (Receive mode only). 5. Outputs will drive logic operating at 5 Volts and inputs will be correctly driven by logic operating at 5 Volts (CMOS & TTL logic levels). Easy-Radio Data sheet ER400TRS 1-1 Copyright LPRS 2002. Iss. 1-1 October 2002 Page 3 of 7 LPRS Preliminary Data Sheet Easy-Radio ER400TRS Transceiver Application Circuit Figure 4 shows the connection of the Easy-Radio ER400TRS Transceiver to a PC AT RS232 port. A MAX232 provides the necessary voltage level shifting required to send and receive serial data at the typical +/- 12V RS232 signal levels. This IC also inverts the RS232 signal to match those required by the EasyRadio Transceiver. 7805 +5V Antenna VO 10uF 16V ANT RF GND RSSI BUSY DATA OUT DATA IN HOST RDY VCC GND Vin = 8-12V DC Electrolytic Capacitors 1 2 G N D VI 100n 1 2 3 4 5 6 7 8 3 4 5 6 7 8 9 C1+ V+ C1C2+ C2VT2OUT R2IN VCC GND T1OUT R1IN R1OUT T1IN T2IN R2OUT 16 15 14 13 12 11 10 9 1N4148 100n 1 6 2 7 3 8 4 9 5 100n MAX232 DCD DSR RXD RTS TXD CTS DTR RI GND PC AT ER400TRS 0 Volt 100n Host Ready Tied Low ERTxcvr2.sch Figure 3 Application Circuit Notes 1. Do NOT connect the Easy-Radio Transceiver directly to an RS232 port as it may cause permanent damage to the transceiver. 2. The ‘Host Ready Input’ handshake line is shown tied to 0 Volt (Ground) thus allowing any data received to be immediately sent to the RS232 port. PCs have sufficient internal buffering to accept and process this data without the need for flow control. 3. The ‘Busy Output’ handshake line is not connected. If data is sent whilst the transceiver is busy (e.g. transmitting), it will be lost. 4. The PC handshake lines (CTS, RTS) are hard wired to defeat any software that may test the state of these lines. 5. Windows ‘HyperTerminal’ software built into the Windows operating system provides a useful method of sending and receiving data to and from a PC during testing. Set the data format Properties to ‘19200 8-N-1’ and use ‘Direct Connection’ to the chosen Com port. Use a 1:1 cable (not ‘crossover’) to connect to the PC Com port. 6. The addition of LEDs to the handshake lines provides a useful diagnostic tool. Easy-Radio Data sheet ER400TRS 1-1 Copyright LPRS 2002. Iss. 1-1 October 2002 Page 4 of 7 LPRS Preliminary Data Sheet Easy-Radio ER400TRS Transceiver Absolute Maximum Ratings Operating Temperature Range Storage Temperature Range -20° C to +65° C (Commercial) -20° C to +75° C Vcc (Pin 17) All Other Pins Antenna - 0.3 to + 6.0 Volts - 0.3 to 3.3 Volts 50V p-p @ < 10MHz Performance Data Supply +5.0 Volt ± 5%, Temperature 20° C DC Parameters Pin Min Typical Max Supply Voltage (Vcc) Transmit supply current Receive supply current Quiescent supply current Interface Levels Data Output Logic 1 Data Output Logic 0 Logic Output Current Data Input Logic 1 Data Input Logic 0 Input Pull-ups RF Parameters Antenna Impedance RF Frequency Transmitter RF Power Output Frequency accuracy FM deviation Harmonics Over Air Data rate Receiver Receive Sensitivity LO leakage RSSI Output Logic Timing Initial Power Up Time Standby Power Up Time Serial Data Rate Mechanical Size Pin Pitch Weight 17 17 17 17 3.3 5.0 23 12.5 2 5.5 3.1 0.1 10 2.0 0.2 Pin 2 Min 2 100 Typical 50 433.92 Max +10 ±50 -30 -25 19200 -94 -60 11 Pin 0 Min Typical 7.5 TBA 19,200 37 x 14 x 4 2.54 5 1.2 Max Units Volts mA mA mA Notes 1 Volts Volts mA Volts Volts K Ohm Units Ohms MHz 10k load to +Vcc supply 10k load to +Vcc supply dBm ppm kHz dBc bps 50 Ohm load Overall dBm dBm Volt Units mS BER = 10-3 Meets EN 300 220-3 See Figure 6 Notes 3,4 5 Host interface bps 2 Notes Manchester Encoded mm mm gms Standard 0.1 Inches Notes 1. Processor running at full speed. Contact the Sales Office for details of special low power variants. 2. The ‘Host Ready Input’ and the ‘Serial Data Input’ have ‘weak’ internal pull-ups enabled. These inputs should not however be left ‘floating’ but should be tied to either Vcc or Ground 0 Volts. 3. When power is first applied to the module the processor retrieves ‘calibration’ data for the RF section that compensates for temperature and power supply voltage variations. The transceiver will then be ready to receive (default) or transmit. It would normally be left in this powered state ready to receive data. 4. During power up the Busy Output line goes high. 5. Contact the Sales Office for special ‘fast’ versions that can incorporate internal ‘duty cycling’ to further reduce quiescent power consumption for battery powered applications. Easy-Radio Data sheet ER400TRS 1-1 Copyright LPRS 2002. Iss. 1-1 October 2002 Page 5 of 7 LPRS Preliminary Data Sheet Easy-Radio ER400TRS Transceiver Notes RSSI Output The transceiver has a built in RSSI (Received Signal Strength Indicator) that provides an analogue output voltage that is inversely proportional to the RF energy present within the pass band of the receiver. It ranges from 0 Volt (maximum signal, –50dBm) to 1.2 Volts (minimum signal, -105bBm) and has a slope of approximately 50dB/Volt. This analogue output signal should only be connected to a high impedance load (>100k Ohms) and can be used to provide a measure of the signal strength and any interfering signals (noise) within band during the installation and operation of systems. Voltage 433MHz 1.3 1.2 1.1 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 -105 -100 -95 -90 -85 -80 -75 -70 -65 -60 -55 -50 dBm Figure 4 RSSI Output PCB Layout The Ground (0 Volt) pins of the transceiver should be connected to a substantial ground plane (large area of PCB copper) connected to 0 Volt. It is suggested that a double-sided PCB be used with one layer being the ground plane. Power Supply The supply used to power the transceiver should be ‘clean’ and free from ripple and noise (<20mV p-p total). It is suggested that 100nF ceramic capacitors be used to de-couple the supply close to the power pins of the transceiver. The use of ‘switch mode’ power supplies should be avoided as they can generate both conducted and radiated high frequency noise that can be very difficult to eliminate. This noise may considerably reduce the performance of any radio device that is connected or adjacent to the supply. Antennas The transceiver can be used with the various common types of antenna that match the 50 Ohm RF Input/Output such as a monopole (whip), helical or PCB/Wire loop antennas. Monopole antennas are resonant with a length corresponding to one quarter of the electrical wavelength (λ/4). They are very easy to implement and can simply be a ‘piece of wire’ or PCB track which at 434MHz should be 16.4 cms in length. This should be straight, in ‘free space’ (kept well away from all other circuitry) and should be connected directly to the Antenna pin of the transceiver. If the antenna is remote it should be connected via a 50 Ohm coaxial feeder cable or transmission line. A 50 Ohm transmission line can be constructed on FR4 board material by using a 3mm wide PCB track over a ground plane. This should be kept as short as possible. Helical antennas are also resonant and generally chosen for their more compact dimensions. They are more difficult to optimise than monopole antennas and are critical with regard to surrounding objects that can easily ‘de-tune’ them. They operate most efficiently when there is a substantial ground plane for them to radiate against. Wire or PCB Loop antennas are the most compact antennas but are less effective than the other types. They are also more difficult to design and must be carefully ‘tuned’ for best performance. The Internet can provide much useful information on the design of Short Range Device (SRD) Antennas. Easy-Radio Data sheet ER400TRS 1-1 Copyright LPRS 2002. Iss. 1-1 October 2002 Page 6 of 7 LPRS Preliminary Data Sheet Easy-Radio ER400TRS Transceiver Product Order Codes Name Description Order Code Easy-Radio 400 Transceiver (Single-In-Line) UK/European Transceiver Module on 433 MHz ER400TRS Please contact the sales office for availability and other variants of the standard product. The software interface can be customised to specific requirements for high volume applications. Document History Issue Date Revision 1-0 1-1 October 2002 October 2002 Preliminary Additions to specifications Copyright The information contained in this data sheet is the property of Low Power Radio Solutions Ltd and copyright is vested in them with all rights reserved. Under copyright law this documentation may not be copied, photocopied, reproduced, translated or reduced to any electronic medium or machine readable form in whole or in part without the written consent of Low Power Radio Solutions Ltd. The circuitry and design of the modules are also protected by copyright law. Disclaimer Low Power Radio Solutions Ltd has an on going policy to improve the performance and reliability of their products; we therefore reserve the right to make changes without notice. The information contained in this data sheet is believed to be accurate however we do not assume any responsibility for errors or any liability arising from the application or use of any product or circuit described herein. This data sheet neither states nor implies warranty of any kind, including fitness for any particular application. +44 (0)1993 709418 +44 (0)1993 708575 www.lprs.co.uk [email protected] Low Power Radio Solutions Ltd Two Rivers Industrial Estate Station Lane Witney Oxon OX28 4BH England Copyright LPRS 2002. Iss. 1-1 October 2002 Page 7 of 7 For further information or technical assistance please contact: Tel: Fax: Web: Email: End of Data Sheet Easy-Radio Data sheet ER400TRS 1-1